CVE-2004-1428 in FTP Server
Summary
by MITRE
ArGoSoft FTP before 1.4.2.1 generates an error message if the user name does not exist instead of prompting for a password, which allows remote attackers to determine valid usernames.
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Analysis
by VulDB Data Team • 07/06/2025
The vulnerability described in CVE-2004-1428 affects ArGoSoft FTP server versions prior to 1.4.2.1 and represents a classic information disclosure flaw that undermines the security of authentication mechanisms. This issue stems from the server's improper handling of user authentication responses, where the system provides different error messages based on whether a username exists in the system. The vulnerability specifically manifests when an attacker attempts to authenticate with a non-existent username, causing the server to generate a distinct error message that indicates the username is invalid rather than simply rejecting the authentication attempt without revealing information about user accounts.
From a technical perspective, this vulnerability constitutes a timing and response analysis attack vector that violates fundamental security principles of authentication systems. The flaw operates on the principle that legitimate users should receive consistent error responses regardless of whether their credentials are valid or invalid. When the server responds differently to attempts with non-existent usernames compared to attempts with valid usernames but incorrect passwords, it creates a side-channel information leak. This behavior directly aligns with CWE-200, which addresses the disclosure of information to unauthorized actors, and represents a clear violation of the principle of least privilege in authentication systems. The inconsistent error messaging creates a predictable pattern that attackers can exploit to enumerate valid user accounts through systematic probing.
The operational impact of this vulnerability extends beyond simple user enumeration, as it provides attackers with foundational information necessary for subsequent attack phases. Once valid usernames are discovered, attackers can proceed with more sophisticated attacks such as password spraying, brute force attempts, or credential stuffing attacks against the identified accounts. This vulnerability particularly affects environments where FTP servers are exposed to untrusted networks or the internet, as the information disclosure occurs without requiring authentication or special privileges. The attack can be automated through simple scripts that attempt to authenticate with various username combinations, making it a particularly dangerous vulnerability for organizations with publicly accessible FTP services.
Security professionals should consider this vulnerability in the context of the broader ATT&CK framework, specifically under the reconnaissance phase where adversaries gather information about target systems. The ability to enumerate valid usernames directly supports techniques such as credential access and privilege escalation, as demonstrated by the ATT&CK technique T1078 for valid accounts and T1566 for credential harvesting. Organizations should implement proper error handling that provides consistent responses regardless of whether a username exists, ensuring that authentication systems do not inadvertently leak information about account validity. The recommended mitigation involves upgrading to ArGoSoft FTP server version 1.4.2.1 or later, which includes proper error handling that prevents the disclosure of user account information. Additionally, network segmentation and access controls should be implemented to limit exposure of FTP services to trusted networks only, reducing the attack surface available to potential adversaries.